I have not tried it yet, but the question I have is that, my SFTP service provider sent me, along with the connection data, a file with the name "101594424Key" that I must use to authenticate myself, it even tells me that the password leave blank. My question is how I use this file within the code shown above. Someone with experience in SFTP could give me a hand please.

/*https://serverfault.com/questions/27396 ... command-li
You can simply use the -i argument for your sftp or ssh command.
sftp -i /path/to/private/keyfile ...
If the -i option is not available, you can use the -o option with a syntax like:
sftp -oIdentityFile=/path/to/private/keyfile ...
*/